U.S. U.S. patent application Ser. No. 609,610, filed May 14, 1984 now U.S. Pat. No. 4,593,078, provides a polyglycidyl ether having on average n epoxy groups per molecule, where 1&lt;n.ltoreq.2, which comprises the reaction product of a multifunctional polyglycidyl ether having on average x epoxy groups per molecule, where x&gt;2, with (x-n) mol of monofunctional phenol per mol of the multifunctional polyglycidyl ether. One use of such polyglycidyl ethers is in a process for preparing a resinous compound for use in a thermosetting coating composition, which process comprises reacting such a polyglycidyl ether in aqueous medium with an amino compound containing on average two amino-hydrogen atoms per molecule at a temperature in the range 100 to 120.degree. C. Thermosetting coating compositions are prepared by combining such resulting resinous compounds with a cross-linking compound in a weight ratio of from 95:5 to 65:35 before of after neutralization.
If desired, a quantity of a known liquid or solid diglycidyl ether, such as a liquid or solid bisphenol-A-derived diglycidyl ether, e.g. those marketed under the trade designation of EPON.RTM. Resin 828, EPON.RTM. Resin 1007, etc., may be included with the above polyglycidyl ether in the reaction in aqueous medium in the above process for preparing a resinous compound.
EPON.RTM. Resin 828 is a liquid diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane having an epoxy equivalent weight of 182 g to 194 g. EPON.RTM. Resin 1007 is a solid diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane having an epoxy equivalent weight of 1500 g to 2000 g. "Epoxy equivalent weight" ("WPE") is the weight in grams of glycidyl compound containing 1 g-equivalent of epoxide.
It has now been found that use of a diglycidyl ether having WPE in the range 300 g to 1500 g in a specific range of weight ratios of polyglycidyl ether:diglycidyl ether enables cured coatings having surprisingly enhanced flexibility to be obtained from stable thermosetting coating compositions.